The present invention relates to heart valve replacement and, in particular, to collapsible prosthetic heart valves. More particularly, the present invention relates to collapsible prosthetic heart valves.
Prosthetic heart valves that are collapsible to a relatively small circumferential size can be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into a patient via a tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This collapsibility can avoid the need for a more invasive procedure such as full open-chest, open-heart surgery.
Collapsible prosthetic heart valves typically take the form of a valve assembly or structure mounted on a stent. There are many types of stents that may be used. However, two types of stents on which the valve structures are ordinarily mounted include: a self-expanding stent and a balloon-expandable stent. To place such valves into a delivery apparatus and ultimately into a patient, the valve must first be collapsed or crimped to reduce its circumferential size.
When a collapsed prosthetic valve has reached the desired implantation site in the patient (e.g., at or near the annulus of the patient's heart valve that is to be replaced by the prosthetic valve), the prosthetic valve can be deployed or released from the delivery apparatus and expanded to the full operating size. For balloon-expandable stents, this generally involves releasing the entire valve, assuring its proper location, and then expanding a balloon positioned within the stent. For self-expanding stents, on the other hand, the stent automatically expands as the sheath covering the valve is withdrawn.
The leaflets in a collapsible prosthetic heart valve, over their useful life, must open and close millions of times. This repeated movement can cause various stresses on the leaflets and, in particular, where they are secured to the rest of the valve. Improper or inadequate attachment can lead to tearing of pulling away from the stent and failure of the valve. And valve failure, in the circulatory system, can have significant consequences for the patient. Accordingly, there remains a need for improved methods of producing heart valves and securing valve leaflets in collapsible prosthetic heart valves.